Warping Space, Time, and Distance

Originally posted by CLPrime
This restraining force is called the Normal force, and it's mostly found in high school physics.

edit on 6-5-2012 by CLPrime because: (no
reason given)

The only thing I remember of high school science was that the teacher was a drunk. I was in a bathroom stall and smoking a cigarette. I came out just
in time to catch Mr. Nash taking a swing of brandy. He turned to me and said, "I won't tell if you won't."

That's an unresolved question, though we know that the basis for the strengths of all the forces are their coupling constants. It just happens that
the gravitational coupling constant leads to the weak gravitational force required for large-scale structure formation.

why does gravity only pull ( it doesnt seem to have an anti mechanism)

Because all matter is positive. If there were negative matter, it would actually lead to three possibilities: attraction, repulsion, and
running-away-sion (if you want me to explain that, I will...seriously).

What is the instantaneous action at distance, what mediates gravity- is there a Graviton???

I run contrary to mainstream physics in that I believe there is a graviton responsible for even large-scale gravity (Quantum Physics predicts a
graviton for quantum-scale interactions only).
Mainstream physics says that gravity is the curvature of spacetime...that is not action-at-a-distance, and it requires no mediator, so those issues
are moot.

BTW I;d be interested to hear from the resident Gravity experts on exactly which dimension the (Already 3 Dimenisonal) Planet seems to sag in
to create the "gravity well " in the Euclidian geometery expalantion as shown in jiggerj's pic...we seem to have a 3d object with its own x,y,z
coordinates moving through another dimension whilst alos affecting another 3d object ??

I've already explained that that's an inaccurate visualization. There is really no "sagging." The curvature is in all four dimensions (3 space and
1 time). This curvature of the tensor field causes acceleration toward the center of mass.

The Sun warps space out to an infinite distance. This warping approximately follows the inverse square rule: at twice the distance, the force of
gravity is 1/4 as strong.

Neptune is 30 times further out from the Sun than the Earth is. That means, at that distance, the force of gravity is 1/(30^2) = 1/900 the strength it
is here.

If you know what a force is, you'll know that it's the amount of "push" needed to accelerate a certain mass by a certain amount: F = ma, where F
is the force in Newtons, m is the mass in kg, and a is the acceleration of the mass in m/s^2.
Also, you should keep in mind that it is a force that keeps a planet in orbit - specifically, centripetal (center-seeking) force. Even more
specifically, that centripetal force here is the gravitational pull of the Sun.

So, the force at the distance of Neptune is 1/900 the strength it is here at the distance of the Earth. That's the centripetal force that holds
Neptune in its orbit.
Recalling that F = ma, rearranging that gives the acceleration as a = F/m. That means the centripetal acceleration of the orbiting planet is
proportional to the force of gravity at that distance. At the distance of Neptune, then, the centripetal acceleration is much less than it is at the
distance of the Earth.

Now, centripetal acceleration is equal to (v^2)/r, where v is the orbital velocity of the planet and r is its distance from the Sun. Orbital velocity
is proportional to the square-root of the centripetal acceleration. That means that the orbital velocity of Neptune will be proportional to the
square-root of 1/900, or 1/30, as compared to the orbital velocity of the Earth.

Ultimately, this is what I'm getting at: the only thing that must be satisfied in order to keep Neptune in an orbit around the Sun is that particular
orbital velocity. Any slow and it falls into the Sun; any faster and it will fly off into space.
You will find that this is true by checking the orbital velocity of Neptune as compared to the Earth. For the Earth, it's 30 km/s; for Neptune, it's
5.43 km/s. The fact that Neptune's orbital velocity isn't exactly 1/30 that of the Earth is because it's more massive. If the Earth suddenly found
itself out at the distance of Neptune, its new orbital velocity will be exactly 1/30 what it is now, which would just happen to be 1 km/s.

As I said, the gravity well of the Sun extends out to infinity. Any object, even one millions of light-years away, can conceivably enter into an orbit
around the Sun. However, at that distance, too may other stars get in the way.

I'd be interested to hear from the resident Gravity experts on exactly which dimension the (Already 3 Dimenisonal) Planet seems to sag in to create
the "gravity well " in the Euclidian geometery expalantion as shown in jiggerj's pic...we seem to have a 3d object with its own x,y,z coordinates
moving through another dimension whilst alos affecting another 3d object ??

The "elastic sheet" analogy for gravitation is really a rather crude representation and ultimately breaks down as an explanation because it is only
a metaphor.

As CLPrime explained in a previous post, the full understanding of how space-time curves and causes gravitation is best understood by visualizing some
complex 3D calculus.

But before you get all wound up with the C word, just relax and think that when you catch a ball, you have mapped out the path of the ball in your
mind and have placed your hand/s at the right place, at the right time, to intercept the flight of the ball - in other words, you have just solved
some complex 3D calculus.

So, try and imagine space as a 3D grid, or matrix, of regular cubes. All the sides of each cube are, of course, the same length.

Now, into the middle of the grid (somewhere) we introduce our strong gravity which pulls on the grid structure and sucks it in slightly towards the
center of gravity. This is like a mental map of space-time. Points further away from the gravitational source are more like the true cubic shape.
Points closer in, are drawn in closer to the gravity and are also drawn in closer to each other too, so the shape of each cell "warps" away from the
original cubic one (It's a bit like those old maps which showed giant land masses at the poles because they "flattened out" the image of a round
earth onto a flat piece of paper).

Any object falling through this warped space follows a path of least resistance, if it is going straight and not accelerating it will continue
straight and not accelerating. But the very substrate of space-time itself is warped and so the path of least resistance is relative not to "ideal"
un-warped space, but is relative to the bent structure of space-time through which it moves.

In this case, the direction of the moving object follows the curvature of space-time.

When we observe the object we see its path deflecting towards the source of gravitation and so we say it is "attracted" towards the source but this
just the way we perceive it from our point of view.

Think about this quote from the physicist John Wheeler for a bit: "Space-time tells matter how to move. Matter tells space-time how to curve".

I'm not sure what part of the Gravitron is supposed to relate with gravity. I can't see any obvious similarity.

if all the celestial bodies of the universe were paused as they are, and there was no movement yet time traveled on, would there still be such a thing
as gravity?

I pictured the gravitron as similar to the planet,,,, if the gravitron was rotating and traveling as a body through space, i imagine it is similar to
why tiny things compared to the planet are destined to not travel far from the surface.

if all the celestial bodies of the universe were paused as they are, and there was no movement yet time traveled on, would there still be such a thing
as gravity?

Certainly. Gravity doesn't depend on motion...it causes it.

I pictured the gravitron as similar to the planet,,,, if the gravitron was rotating and traveling as a body through space, i imagine it is
similar to why tiny things compared to the planet are destined to not travel far from the surface.

The Gravitron works because of centripetal acceleration (the ride's rotation). Gravity is a centripetal force. The two aren't really comparable.

Einsteins theory of relativity involved that very premise of gravity bending light. A huge effort was undertaken to capture that effect during
succeeding eclipses. They were ultimately successful and the proof was determined with just the distance from the earth to the sun. About 92 million
miles. I don't have a link for all that just now... if someone already mentioned it please forgive me. The light traveling throughout the Universe
has been bent around so many times I wonder if the actual size of it is much smaller. We just think that is a different part of space but really we
are just seeing ourselves from a different angle? Dunno...

Heres an example of what I was wondering. Scroll down to second picture. Does it not appear that the upper left quadrant and lower right quadrant are
the same object from two different perspectives? Because of light "lensing"?

Sure, I'd like all those questions answered. But I still want to know how the sun can have any affect whatsoever on a cosmic body billions and
billions of miles away.

Gravity is an awesome thing. Somewhere I read that if you could possibly empty the whole of the cosmos of all matter and then place two atoms at
either end of that space absolutely still (relative to each other), that they would then sloooooowly begin to move towards each other, faster and
faster until they met and joined. I don't' know if anyone knows why that is so. The inference is that all matter in the Universe is connected by
gravity on some level. Even you and I.

Gravity even bends light as we know. But I think that folding space or warping space as it were, is something entirely different. Look at trees
blowing in the wind for instance. They bend and bow before the wind , their trunks assuming arcs like the light in some of the space pictures coming
to us today. But the tree trunks go back to being straight after the wind dies down. Don't know if this is a good analogy or not. Just thought it
up.

So yah, light wraps around strong centers of gravity because light has mass (photons), but folding space or time is not apparent. Not that that
doesn't happen, just not here apparently. From our view point in the third dimension it is hard to see beyond space time. We use our eyeballs to
"see" and think we know how things "work".

The Sun warps space out to an infinite distance. This warping approximately follows the inverse square rule: at twice the distance, the force of
gravity is 1/4 as strong.

So everything is connected via gravity. And the strong rule right? You obviously know your stuff. I was wondering some things...
The stars in the disk of "ordered" galaxies seem to stay "apart" relative to each other. Is that an accurate description? What is the force that
maintains distance spacing of suns, despite gravity. This is not a la grange question.
And if we take a string and swing a stone around our heads, is that another way to describe gravity that excludes the warping of space explanation?
Gravity well is an analogy, right? That gravity could be a "string" of sorts between objects with deference to the larger masses?

And lastly, my underedumacatedist question of them all, I have seen astronauts eat globs of water until I thought I was going to throw up, but never
seen them swing a ball on a string around their head. Is that possible In free fall?

The stars in the disk of "ordered" galaxies seem to stay "apart" relative to each other. Is that an accurate description? What is the force that
maintains distance spacing of suns, despite gravity.

Yes & No.....The galaxies are actually getting further apart(expanding universe) and we are unsure as to whether they will stop one day and start
falling back to a singularity.

Centripetal Acceleration. The principle is exactly the same for a galaxy as it is for a solar system.

If we think of our string as gravity and the centripetal force as the motion of our ball pulling on the string balancing the force of gravity.

This is not a la grange question. And if we take a string and swing a stone around our heads, is that another way to describe gravity that
excludes the warping of space explanation? Gravity well is an analogy, right? That gravity could be a "string" of sorts between objects with deference
to the larger masses? And lastly, my underedumacatedist question of them all, I have seen astronauts eat globs of water until I thought I was going to
throw up, but never seen them swing a ball on a string around their head. Is that possible In free fall?

Yes. Though in a free fall, the string and ball will make a cone shape(even if only very slightly) if the plane of rotation were perpendicular to the
free fall. If it was parallel, the motion would accelerate on one side and decelerate(actually its accelerate in the opposite direction - there is no
such thing as deceleration) on the other.

Thankyou for those answers. At the risk of being redundant, I wanted to take the question of Star "spacing" in the disk of a galaxy a bit further.
From my own observation, I can see in a room full of dust that is swirling in the natural air currents that dust particles are close but not touching
as they move thru the currents. As thought they are held apart by (static) some force that denies them clumping together in the air of the room. I see
the disk of a galaxy in a photo where the stars appear as milk or vapor droplets in a cloud even and I wonder what is the medium that underlies the
accretion disk that maintains that balance of spacing? Sorry if I am off beat, just this sticks in my mind.

What is the medium that keeps the stars separate from each other in a galaxy?

What is the medium that keeps the stars separate from each other in a galaxy?

There isn't. The stars are still under each others gravitational influence, but their orbital velocity is opposing the gravitational pull of the bulk
of the galaxies combined gravitational pull.

That is a little vague.

Ok try this.....get a half of a bucket of water and swirl your hand in it until you get a nice cone shape in the spinning liquid. Put a light object
(low density) in the bucket and it will move toward the rim from the centripetal force. Now if we put a heavier object in, it slides down the liquid
cone shape until it reaches the bottom.

These first two scenarios describe matter in the galaxy in its early stages. Some matter gets flung outward and heads toward the galactic rim, some
matter clumps together and forms stars.

Going back to our bucket......If we get the velocity of the water right....and the density of our celestial body right, then the celestial body will
appear to float on the surface of the water halfway between the rim and the base of the vortex.

As long as the velocity of the water remains the same, our improvised celestial body will stay in the "golden zone".

The galaxy is much the same as our bucket except that the gravity is perpendicular to the water. As long as the bodies in motion around our galaxy
maintain their velocity, then they will stay orbiting around the centre of the galaxy(Sag' B I think). Unfortunately, the combined gravitational
pulling of all of the bodies in a galaxy will gradually slow the "accretion disks" spin and(it is theorised) that it will all end up as one giant
black hole, or possibly.......a singularity.

I love your bucket of water analogy. I learned from Einstein that if I try to analogize my perceptions of the real, that I can better understand them
on my level. I try to find the as above so below similarities in the way things operate. To "unify" if you will the mechanisms by which systems
operate. Your water "whirlpool" is one of these. I can see the similarities between say, a galaxy and a hurricane or the rings of Saturn and the
solar system for instance. All of these depend upon similar (how to say) rules. All of them form a "disk" of sorts of finely divided material that
sweeps around their central hub.

In your bucket the medium is water and it has a well defined surface or region that things "float" like you say. Given the right density objects
will suspend in the "boundary layer" and travel along a similar path. If you dribble a fine medium like flour in the mix it will tend to clump up
and not stay smooth, eventual forming an outer ring at the limit of the bucket. (Sombrero Galaxy?) In the rings of Saturn there are "shepard" moons
at the outer edges of the farthest ring that appear to be formed by the rings themselves. In the solar system Kuiper belt and Oort cloud where (it is
theorized) there are objects larger than the gas giants of the "inner" solar system. In the Solar System, planets are differing sizes. I guess that
is true of the Galaxy then also? There are black holes, massive stars and tiny brown dwarfs all suspended in the "medium" of gravity. It all happens
real slow from our perspective and this changes the dynamics. Water drops in a hurricane behave similarly in the medium of wind.

Like your water bucket. Water is easy to see and manipulate. Too bad we can't put a measure on gravity the same way. We only see its effects. Water
forms oceans and rivers and water falls. I wonder if gravity does too under certain circumstances. Like jets from centers of galaxies?

So there is no medium of gravity like with water. It operates perpendicular to the whirlpool. Something I can't quite put my mind around here. Theres
that missing element, even you say that this is (theorized). I agree. Thanks for your time. I really appreciate you making me think.

OccamAssassin took care of most of this, but here's a little more from yours truly...

Originally posted by intrptr

The stars in the disk of "ordered" galaxies seem to stay "apart" relative to each other. Is that an accurate description? What is the force that
maintains distance spacing of suns, despite gravity. This is not a la grange question.

There is no force that maintains that distance. Pretty much all that maintains that distance is the distance. Stars are separated by light-years worth
of practically empty space. The intrinsic relative motion of any star is more than capable of evading any gravitational pull at that distance.

And if we take a string and swing a stone around our heads, is that another way to describe gravity that excludes the warping of space
explanation? ... That gravity could be a "string" of sorts between objects with deference to the larger masses?

No. That's an alternate theory, but it's not a working one. It's a barely acceptable model of an orbit, but that's it.

Gravity well is an analogy, right?

It's a term used to describe the map of the gravitational potential, which is shaped like a well (that is, a simple depression, like an upside-down
bell curve, not a water well). A gravity well described a region of spacetime having an increasingly higher gravitational potential, usually
surrounding a point-mass.

And lastly, my underedumacatedist question of them all, I have seen astronauts eat globs of water until I thought I was going to throw up, but
never seen them swing a ball on a string around their head. Is that possible In free fall?

It sure is. It should actually be a little easier, without gravity and air resistance.

My burning question is what is it that we conceive as as nothing IE space
There is of course interstellar material which is sparse compared to planets and stars.
And their are subatomic particles - but what is the medium they exist in composed of.
In a way there is such a thing as nothing yet nothing must be composed of something that we can not measure or name.

There is no medium in which matter exists. Space is the volume that contains all matter...it's not a medium, it's a region. And a vacuum is the
lowest possible energy state of a space.

Is there an up and down to this region? what if we were launching a spaceship that could travel lightyears in seconds from the northpole, and kept
going straight, would we eventually be able to view a birds eye view of the universe? what if we were in a space ship and traveled outside of our
galaxy and then idled for "a very long time"
would we be eventually moved by surrounding forces, or would we eventually get run into by another galaxy?/ ( is it possible for anything to be
completely still for a long period of time?)

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